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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

A Catabolic Powerhouse for Biorefineries: Characterization and Engineering Erwinia spp. Strain LJJL01 to Produce Bioproducts

Nonmodel microbial hosts can efficiently biotransform unconventional organic feedstocks into advanced bioproducts, leveraging their superior metabolic capabilities and resilience to process-relevant physicochemical conditions. In this study, we domesticated Erwinia spp. strain. LJJL01 (Er LJJL01) as a potent microbial chassis to advance the emerging biorefinery strategy for the valorization of lignin-rich biomass and plastic, thereby enabling the circular economy. The strain exhibits remarkable chemical tolerance and can biofunnel various substrates, including sugars, acids, polyols, and aromatics, in minimal salt media to produce native fine chemicals such as acetoin, 2,3-butanediol, and lactic acid. As a proof of concept, engineering this strain with advanced genetic tools enables the production of tailored high-value chemicals, such as cis,cis-muconate from plastic-derived terephthalate and polyhydroxybutyrate from lignocellulosic hydrolysate. We established Er LJJL01 as a potent microbial chassis for the green synthesis of bioproducts from unconventional organic feedstocks.

09 BIOMASS FUELS↗
DOE OSTI2025

Enhancing the shredder durability for biomass preprocessing by utilizing wear-resistant cutter materials

Shredders are widely used to reduce biomass feedstock size through the shearing action of the cutter teeth that are susceptible to wear. A series of wear tests using a custom-built shredder was conducted on corn stover feedstock with three cutter materials: a conventional D2 tool steel, iron boriding as a candidate surface treatment, and M42 tool steel as a candidate alloy. Wear tests showed that the iron borided D2 steel significantly increased the tool life compared with the non-treated D2 and M42. Although the M42 cutters initially exhibited less wear than the D2 cutters, the benefit faded as preprocessing progressed. In conclusion, the experimental results demonstrated that the durability of shredder cutters can be substantially improved by applying more wear-resistant tool materials.

09 - BIOMASS FUELS↗
DOE OSTI2025

Compressibility and permeability of particulated non-recyclable municipal solid waste

Biofuels from non-recyclable municipal solid waste (NMSW) stand at the forefront of energy sustainability. However, their widespread adoption is hampered by persistent material handling issues stemming from the variability in NMSW material properties. An enhanced understanding of particulated NMSW properties, particularly compressibility and permeability, is essential to address the feedstock handling challenges and optimize the handling equipment. This study measures the compressibility and gas permeability of five streams of NMSW materials (i.e., rigid plastics, cardboard, thin film, paper, and foam) and their mixtures under different stress conditions. The results highlight the significant variability in compressibility and gas permeability among different streams, as well as the impacts of particle sizes. A semi-empirical model capable of predicting the gas permeability of NMSW mixtures is established and validated. Here, the results also highlight that reduced NMSW particle size helps promote consistency in NMSW feedstock’s physical and mechanical properties, which is favored for handling equipment design in waste-to-energy recovery facilities.

09 BIOMASS FUELS↗
DOE OSTI2026

Production of high-quality polyethylene (PE) films from post-consumer shrink wrap with solvent targeted recovery and precipitation (STRAP)

The solvent-targeted recovery and precipitation (STRAP™) process separates polymers from contaminants present in the feedstock. In this work, we demonstrate the recyclability of a post-consumer waste (PCW) shrink wrap that contains inks, adhesives, and paper using STRAP. We produced a clear rPE cast film from the PCR shrink wrap with no visual contamination from paper or inks. STRAP decreased the ash content from 0.96 wt% to 0.24 wt%. A techno-economic analysis (TEA) shows that a STRAP plant processing 50,000 metric tons annually of shrink wrap waste (purchased at $\$0.25$/kg) containing 85 wt% PE can achieve an IRR of 16.2% when selling rPE at $\$1.30$/kg, an IRR of 10.7% with an rPE price of $\$1.00$/kg, or an IRR of 3.79% with an rPE price of $\$0.70$/kg. Furthermore, the life cycle assessment (LCA) shows a 64% reduction in global warming potential (kg CO 2 equivalent) when compared to the production of virgin LDPE. As a result, this work shows how feedstocks with insoluble impurities can be recycled using STRAP on a large scale.

Radkevich, Elizaveta [University of Wisconsin-Madi↗
DOE OSTI2023

Improving knife milling performance for biomass preprocessing by using advanced blade materials

Mechanical preprocessing of biomass, including size reduction, is a crucial step in converting biomass into biofuel. However, feedstock inevitably contains abrasive intrinsic and extrinsic inorganics that may cause excessive tool wear in preprocessing. Here, this work demonstrates that performance of a knife mill can be significantly improved by applying a more wear-resistant blade material. A series of full-scale knife mill tests were performed for size reduction of forest residue using blades of tungsten carbide (WC–Co), iron-borided tool steel, and diamond-like carbon (DLC) coated tool steel. Blade material loss was quantified in correlation to the amount of feedstock processed and wear mechanisms were investigated via worn surface characterization. While the thin DLC coating was removed quickly, the WC-Co and iron-borided blades improved the tool life by 8X and 3X compared with the M2 tool steel blades (baseline), respectively. The in-situ throughput and power consumption measurements provided additional insights. The WC-Co and iron-borided blades had ~3X higher throughput than the baseline blades by the end of the test with lower normalized power consumption. The experimental results were then used as input for a techno-economic analysis, which suggested that the more wear resistant blades could cut the knife milling cost by $2–3 per ton of biomass processed with downtime reduced by 65–85%.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Lepidopteran mevalonate pathway optimization in Escherichia coli efficiently produces isoprenol analogs for next-generation biofuels

Terpenes constitute the largest class of natural products with over 55,000 compounds with versatile applications including drugs and biofuels. Introducing structural modifications to terpenes through metabolic engineering is an efficient and sustainable way to improve their properties. Here, in this study, we report the optimization of the lepidopteran mevalonate (LMVA) pathway towards the efficient production of isopentenyl pyrophosphate (IPP) analogs as terpene precursors. First, we linked the LMVA pathway to NudB, a promiscuous phosphatase, resulting in the production of the six-carbon analog of 3-methyl-3-buten-1-ol (isoprenol), 3-ethyl-3-buten-1-ol (C6-isoprenol). Using C6-isoprenol as the final product, we then engineered the LMVA pathway by redirecting its upstream portion from a thiolase-dependent pathway to a beta-oxidation pathway. The beta-oxidation LMVA pathway transforms valeric acid, a platform chemical that can be produced from biomass, into C6-isoprenol at a titer of 110.3 mg/L, improved from 5.5 mg/L by the thiolase LMVA pathway, which used propionic acid as a feedstock. Knockout of the E. coli endogenous thiolase genes further improved the C6-isoprenol titer to 390 mg/L, implying efficient production of homo isopentenyl pyrophosphate (HIPP). The beta-oxidation LMVA-NudB pathway also converts butanoic acid and hexanoic acid into isoprenol and isoprenol’s seven-carbon analog, 3-propyl-3-buten-1-ol (C7-isoprenol), respectively, suggesting the beta-oxidation LMVA pathway produces IPP and C7-IPP from the corresponding fatty acids. Fuel property tests revealed the longer chain isoprenol analogs have lower water solubilities, similar or higher energy densities, and comparable research octane number (RON) boosting effects to isopentenols. This work not only optimizes the LMVA pathway, setting the basis for homoterpene biosynthesis to expand terpene chemical space, but provides an efficient pathway to produce isoprenol analogs as next-generation biofuels from sustainable feedstocks.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Advances in systems metabolic engineering of autotrophic carbon oxide-fixing biocatalysts towards a circular economy

High levels of anthropogenic CO 2 emissions are driving the warming of global climate. If this pattern of increasing emissions does not change, it will cause further climate change with severe consequences for the human population. On top of this, the increasing accumulation of solid waste within the linear economy model is threatening global biosustainability. The magnitude of these challenges requires several approaches to capture and utilize waste carbon and establish a circular economy. Microbial gas fermentation presents an exciting opportunity to capture carbon oxides from gaseous and solid waste streams with high feedstock flexibility and selectivity. Here we discuss available microbial systems and review in detail the metabolism of both anaerobic acetogens and aerobic hydrogenotrophs and their ability to utilize C1 waste feedstocks. More specifically, we provide an overview of the systems-level understanding of metabolism, key metabolic pathways, scale-up opportunities and commercial successes, and the most recent technological advances in strain and process engineering. Finally, we also discuss in detail the gaps and opportunities to advance the understanding of these autotrophic biocatalysts for the efficient and economically viable production of bioproducts from recycled carbon.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Carbon-conserving bioproduction of malate in an E. coli -based cell-free system

Formate, a biologically accessible form of CO 2 , has attracted interest as a renewable feedstock for bioproduction. However, approaches are needed to investigate efficient routes for biological formate assimilation due to its toxicity and limited utilization by microorganisms. Cell-free systems hold promise due to their potential for efficient use of carbon and energy sources and compatibility with diverse feedstocks. However, bioproduction using purified cell-free systems is limited by costly enzyme purification, whereas lysate-based systems must overcome loss of flux to background reactions in the cell extract. Here, we engineer an E. coli-based system for an eight-enzyme pathway from DNA and incorporate strategies to regenerate cofactors and minimize loss of flux through background reactions. We produce the industrial di-acid malate from glycine, bicarbonate, and formate by engineering the carbon-conserving reductive TCA and formate assimilation pathways. We show that in situ regeneration of NADH drives metabolic flux towards malate, improving titer by 15-fold. Background reactions can also be reduced 6-fold by diluting the lysate following expression and introducing chemical inhibitors of competing reactions. Together, these results establish a carbon-conserving, lysate-based cell-free platform for malate production, producing 64 μM malate after 8 h. This system conserves 43 % of carbon otherwise lost as CO 2 through the TCA cycle and incorporates 0.13 mol CO 2 equivalents/mol glycine fed. Finally, techno-economic analysis of cell-free malate production from formate revealed that the high cost of lysate is a key challenge to the economic feasibility of the process, even assuming efficient cofactor recycling. This work demonstrates the capabilities of cell-free expression systems for both the prototyping of carbon-conserving pathways and the sustainable bioproduction of platform chemicals.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Mapping glyceride species in biodiesel by high-temperature gas chromatography combined with chemical ionization mass spectrometry.

Accurate and comprehensive identification of residual glycerides in biodiesel is an important part of the fuel characterization, due to the impact of glycerides on the fuel physicochemical properties. However, analysis of bound glycerol in biodiesel samples faces challenges due to lack of readily available standards of structurally complex glyceride species in non-traditional biodiesel feedstocks, and a risk of misannotation in the presence of impurities in gas chromatographic separations. Here we evaluate methane and isobutane chemical ionization – single quadrupole mass spectrometry combined with high temperature gas chromatography separations for mapping monoacylglycerols, diacylglycerols and triacylglycerols in biodiesel. Unlike the electron impact ionization which produces mostly in-source fragments, isobutane chemical ionization spectra of tetramethylsilyl (TMS) derivatized monoacylglycerols and diacylglycerols are dominated by molecular ions and M-SiO(CH3)3+ ions, which provide important diagnostic information. We demonstrate the utility of isobutane chemical ionization in identifying structurally complex glycerolipid standards as well as species in biodiesel samples from different plant and animal feedstocks.

biodiesel, chemcial ionization mass spectrometry↗
DOE OSTI2022

Trace Impurities Identified as Forensic Signatures in CMX-5 Fuel Pellets Using X-ray Spectroscopic Techniques

We report that small-particle analysis is a highly promising emerging forensic tool for analysis of interdicted special nuclear materials. Integration of microstructural, morphological, compositional, and molecular impurity signatures could provide significant advancements in forensic capabilities. We have applied rapid, high-sensitivity, hard X-ray synchrotron chemical imaging to analyze impurity signatures in two differently fabricated fuel pellets from the 5th Collaborative Materials Exercise (CMX5) of the IAEA Nuclear Forensics International Working Group. The spatial distributions, chemical compositions, and morphological and molecular characteristics of impurities were evaluated using X-ray absorption near-edge structure (XANES) and X-ray fluorescence chemical imaging to discover principal impurities, their granularity, particle sizes, modes of occurrence (distinct grains vs incorporation in the UO 2 lattice), and sources and mechanisms of incorporation. Differences in UO 2+x stoichiometry were detected at the microscale in nominally identical UO 2 ceramics (CMX5-A and CMX5-B), implying the presence of multiple UO 2 host phases with characteristic microstructures and feedstock compositions. Al, Fe, Ni, W, and Zr impurities and integrated impurity signature analysis identified distinctly different pellet synthesis and processing methods. For example, two different Al, W, and Zr populations in the CMX5-B sample indicated a more complex processing history than the CMX5-A sample. K-edge XANES measurements reveal both metallic and oxide forms of Fe and Ni but with different proportions between each sample. Altogether, these observations suggest multiple sources of impurities, including fabrication (e.g., force-sieving) and feedstock (mineral oxides). This study demonstrates the potential of synchrotron techniques to integrate different signatures across length scales (angstrom to micrometer) to detect and differentiate between contrasting UO 2 fuel fabrication techniques.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Atomic Level Interactions and Suprastructural Configuration of Plant Cell Wall Polymers in Dialkylimidazolium Ionic Liquids

Ionic liquids (ILs) have been widely investigated for the pretreatment and deconstruction of lignocellulosic feedstocks. However, the modes of interaction between IL-anions and cations, and plant cell wall polymers, namely, cellulose, hemicellulose, and lignin, as well as the resulting ultrastructural changes are still unclear. In this study, we investigated the atomic level and suprastructural interactions of microcrystalline cellulose, birch wood xylan, and organosolv lignin with 1,3-dialkylimidazolium ILs having varying sizes of carboxylate anions. Analysis by 13 C NMR spectroscopy indicated that cellulose and lignin exhibited stronger hydrogen bonding with acetate ions than with formate ions, as evidenced by greater chemical shift changes. Small-angle X-ray scattering analysis showed that while both cellulose and xylan adopted a single-stranded conformation in acetate-ILs, twice as many acetate ions were bound to one anhydroglucose unit than to an anhydroxylose unit. Further, we also determined that a minimum of seven representative carbohydrate units must interact with an anion for that IL to effectively dissolve cellulose or xylan. Lignin is associated as groups of four polymer molecules in formate-ILs and dispersed as single molecules in acetate-ILs, which indicates that it is highly soluble in the latter. In summary, our study demonstrated that 1,3-dialkylimidazolium acetates displayed stronger binding interactions with cellulose and lignin, as compared to formates, and thus have superior potential to fractionate these polymers from lignocellulosic feedstocks.

13C NMR↗
DOE OSTI2020

Electrocatalytic Hydrogenation of Biomass-Derived Organics: A review

Sustainable energy generation calls for a shift away from centralized, high-temperature, energy-intensive processes to decentralized, low-temperature conversions that can be powered by electricity produced from renewable sources. Electrocatalytic conversion of biomass-derived feedstocks would allow carbon recycling of distributed, energy-poor resources in the absence of sinks and sources of high-grade heat. Selective, efficient electrocatalysts that operate at low temperatures are needed for electrocatalytic hydrogenation (ECH) to upgrade the feedstocks. For effective generation of energy-dense chemicals and fuels, two design criteria must be met: (i) a high H:C ratio via ECH to allow for high-quality fuels and blends, and (ii) a lower O:C ratio in the target molecules via electrochemical decarboxylation/deoxygenation to improve the stability of fuels and chemicals. The goal of this review is to determine whether the following questions have been sufficiently answered in open literature, and if not, what additional information is required: (1) What organic functionalities are accessible for electrocatalytic hydrogenation under a set of reaction conditions? How do substitutions and functionalities impact the activity and selectivity of ECH? (2) What material properties cause an electrocatalyst to be active for ECH? Can general trends in ECH be formulated based on the type of electrocatalyst? (3) What is the impact of reaction (electrolyte concentration, pH, operating potential) and reactor type conditions?

Catalysts, redox reactions, hydrocarbons, Aromatic↗
DOE OSTI2025

Recent Advances in the Use of Ionic Liquids and Deep Eutectic Solvents for Lignocellulosic Biorefineries and Biobased Chemical and Material Production

Biorefineries, which process biomass feedstocks into valuable (bio)products, aim to replace fossil fuel-based refineries to produce energy and chemicals, reducing environmental and health hazards, including climate change, and supporting a sustainable economy. In particular, lignocellulose-based biorefineries, utilizing the most abundant renewable feedstock on Earth, have significant potential to supply sustainable energy, chemicals and materials. Ionic liquids (ILs, organic salts with low melting temperatures) and deep eutectic solvents (DESs, mixtures with eutectic points lower than the ideal mixture) are capable of dissolving some of the key lignocellulose polymers, and even the whole biomass. Furthermore, they have intrinsic advantages over molecular solvents, including safer usage profiles and high tunability, which allow tailored physicochemical properties. Such properties provide unique opportunities for the development of new processes that could unlock the full potential of future biorefineries. Here, we review the current state of lignocellulosic biomass processing with ILs and DESs, with a specific focus on the pretreatment chemistry, process flow and products from each component; followed by discussions on sustainability assessments and technological challenges. We aim to inform the research community about the opportunities, challenges and perspectives in developing truly sustainable lignocellulose-based biorefineries.

09 BIOMASS FUELS↗
DOE OSTI2021

Impacts of Anisotropic Porosity on Heat Transfer and Off-Gassing during Biomass Pyrolysis

The pore structure of biogenic materials imbues the ability to deliver water and nutrients through a plant from root to leaf. This anisotropic pore granularity can also play a significant role in processes such as biomass pyrolysis that are used to convert these materials into useful products like heat, fuel, and chemicals. Evolutions in modeling of biomass pyrolysis as well as imaging of pore structures allow for further insights into the concerted physics of phase change-induced off-gassing, heat transfer, and chemical reactions. In this work, we report a biomass single particle model which incorporates these physics to explore the impact of implementing anisotropic permeability and diffusivity on the conversion time and yields predicted for pyrolysis of oak and pine particles. Simulation results showed that anisotropic permeability impacts predicted conversion time more than 2 times when the Biot number is above 0.1 and pyrolysis numbers (Py 1 , Py 2 ) are less than 20. Pore structure significantly impacts predicted pyrolytic conversion time (>8 times) when the Biot number is above 1 and the pyrolysis number is below 1, i.e., the “conduction controlled” regime. Therefore, these nondimensional numbers reflect that when internal heat conduction limits pyrolysis performance, internal pyrolysis off-gassing further retards effective heat transfer rates as a closely coupled phenomenon. Overall, this study highlights physically meaningful opportunities to improve particle-scale pyrolysis modeling and experimental validation relevant to a variety of feedstock identities and preparations, guiding the future design of pyrolyzers for efficient biomass conversion.

09 BIOMASS FUELS↗
DOE OSTI2026

Technology Impact and Resource Assessment of Existing and Planned U.S. Biofuel Production: Life Cycle Water Consumption, Water Stress, Land Use, and Criteria Air Pollutants

Biofuels have the potential to strengthen the U.S. energy supply, enhance energy security, and promote economic development. As the United States continues to expand biofuel production, quantifying resource requirements and location-specific constraints is crucial for planning, siting, and technology development to support long-term viability. Accordingly, this work assesses the life cycle resource consumption (water consumption, and land use), water stress and criteria air pollutants associated with expanded U.S. biofuel production over the 2020–2035 period, based on producers’ plans. We perform a bottom-up technology impact assessment and resource assessment by integrating facility-level production statistics with Argonne’s Research and Development (R&D) GREET model and county-level water-stress characterization factors from Available Water Remaining for the United States (AWARE-US) model. Results suggest that by 2035, biofuels could meaningfully contribute to U.S. energy demand, driven primarily by first-generation and waste-based feedstocks with plans for substantial capacity expansion, although cellulosic and e-fuel technologies remain limited. However, growth must be managed to minimize impacts on water resources and land use. These impacts vary by fuel type and facility location, specifically, projected expansion increases water consumption and can elevate water-stress impacts in certain regions like Nebraska, Kansas, Colorado, Idaho, California and North Texas. Direct land use also increases overall, particularly for first-generation feedstocks such as corn and soybeans. These findings underscore the need for continued technological improvements and innovative strategies to manage resource demands as the industry scales and to support complementary deployment within the evolving U.S. energy system.

09 BIOMASS FUELS↗
DOE OSTI2021

Microbe-Encapsulated Silica Gel Biosorbents for Selective Extraction of Scandium from Coal Byproducts

Establishing an inexpensive and environmentally friendly scandium (Sc) supply is critical for the development of clean energy technologies. However, refining Sc from Sc-bearing sources using current technologies poses economic and environmental challenges due to its low concentration relative to base metals and chemically similar lanthanides. In this work, we developed a biosorption-based flow-through process for extraction of Sc from low-grade feedstocks. A novel biosorbent material was synthesized by encapsulating Arthrobacter nicotianae, a bacterium that selectively adsorbs Sc, within a porous silica matrix. Through the use of several complementary microscopy techniques, we demonstrated a highly porous biosorbent structure with a high cell-loading density and a homogenous cell distribution. Batch adsorption assays revealed selective Sc adsorption over lanthanides and common based metals, with the exception of Fe(III), as evidenced by separation factors greater than 50. The MESG particles were packed into fixed-bed columns to enable adsorption under flow-through conditions, which demonstrated effective Sc extraction at flow rates up to 0.08 cm/s and high stability for reuse; greater than 95% of the adsorption capacity was maintained after 10 consecutive adsorption/desorption cycles. When applied to a lignite coal leachate, whose Fe content was depleted through pH-mediated precipitation, the MESG particles yielded Sc breakthrough at 30 bed volumes, whereas all other metals broke through after only a few bed volumes. Following desorption, an eluate with a 124-fold increase in Sc purity was achieved relative to the lignite leachate with Sc constituting 96.4% of the total REEs. This study established a rapid, facile, and scalable cell immobilization approach that enables the use of microbial biomass for Sc recovery from low-grade sources.

Dong, Ziye↗